The present invention relates generally to a method and apparatus or tool which is used to create a reamed hole for installing a conduit or pipe. The tool and method is well suited for use with directional boring machines, but can be adapted for use with other mechanical devices (such as a push rod machine) that are used to create subsurface excavations for the purpose of installing conduit or pipe.
Often in the past in order to install a new pipe or conduit it has been necessary to excavate from the surface down to the depth of the desired installation and then replace the material that was excavated. This method is often referred to as “open trench excavation” and is not desirable in many locations due to impact to the general public, to pass under obstacles such as roads, environmental concerns and other issues. Devices and tools have been developed in the past by others in order to allow for the installation of underground pipes and conduits without the necessity of open trenching. This method is generally referred to as “trenchless” installation and includes many varied techniques. The primary types of trenchless construction for new pipe and conduit installations involve directional boring machines, push rod machines, pipe ramming devices, auger boring machines, and tunneling methods all known in the art. There are tools and devices known in the utility construction industry for creating reamed holes for the purpose of installing conduits and pipes and, in particular, there are several apparatuses that are used in the directional boring industry. However, no devices are available that embody or use the aspects of the applied for apparatus. The and advantages of the applied for apparatus and method will significantly improve the efficiency and effectiveness of underground utility construction by establishing a better method for creating a trenchless reamed hole for installing pipe and providing a tool for use with the method.
The apparatus and method is best suited for use with directional boring machines, although it may be used with other devices as discussed later. Directional boring machines, in general, utilize a length of drill pipe with at least a small hole passing through longitudinally from one end to the other. Sections of drill pipe are connected and then advanced through the earth in segmental fashion. This segmented connection of drill pipe is called a drill string. Various methods and apparatuses are used to guide the drill pipe into the desired position. Directional boring machines are typically positioned at the surface and advance the drill pipe down to the depth of the desired bore. Often a fluid mixture is passed through the drill string in order to assist in the drilling process. After the initial drill string is in place a hole opening device, typically referred to as a reamer, is attached and used to create a hole that will accept the desired conduit or pipe.
In the past, in general, the primary methods of creating a reamed hole in directional boring applications has been to use a reamer fixedly mounted to the length of drill pipe. The reamer is then, typically, rotated and pulled through the ground. Often an aqueous solution is pumped through the drill string in order to help create a mixture of the existing soil and special added agents that assist in making a slurry that advantageously allows for easier installation of pipe or conduit product. A typical reamer's primary function is often to either chop up the existing soil in the path of the desired bore hole and mix it with the added agents or to compact the existing soil in the path of the desired bore hole. Sometimes reamers are used to combine both compaction and cutting/mixing. Since soil and earth conditions vary greatly, different tools are used and selected based on operator experience and anticipated conditions. Though there are existing tools available, none use a reaming mechanism that incorporates the dual mixing and cutting functions of the applied for apparatus.
Push rod machines incorporate some of the same overall characteristics as directional boring, but typically are placed in an excavation at one end of the desired bore instead of at the surface. Typically a section of pipe is connected in segmental fashion and advanced through the ground. Again, there are various methods to get the rods in the desired place. Often the overall efficiency of the machines and the machine tooling limits the overall length that can be done at one time. The use of push rod machines has diminished in the recent past, but they are still sometimes used and advances in push rod technology, such as ways to ream holes more efficiently, could lead to more prominent use in the future.
The apparatus utilized for practicing the method of installation of conduit or pipe is novel and unique in that it ideally uses either a plurality of stems or a mechanical drive mechanism in conjunction with a single stem to create a much more effective method of both mixing and reaming the soil. This better method and tool therefore decreases the time and increases the efficiency of the installation of conduits and pipe. In addition to these benefits, it is possible to utilize this method and the embodiments of the apparatus to create rectangular, ovoid or even irregularly shaped reamed holes which may be desirable for some installations. There are currently no available apparatuses in the directional boring industry that allow for the creation of other than a generally round reamed hole.